Process for producing stable haloaryl phosphates of low acidity



Un ted S ates, Pate O" -.wall, N.Y., assignorstoTexacoInc a corporation of Delaware N Drawing. ;Application May 31, 1955 Serial No. 512,305

- 4! ma... Cl. 260-461) This invention relates, to a novel method of preparing ahalo-substituted arylphosphate having a low neutraliz ation number. More particularly, it involves a procedure for reducing the neutralization number of halo-substituted aryl phosphates so that they may be used'inlubricants as extreme pressure agents without adversely. affecting the anti-oxidant and anti-corrosive properties of the lubricant.

Halo-substituted aryl phosphates are known to possess extreme pressure and anti-Wear properties. Their use prior-to this invention in lubricants such as internal combustion lubricants and jet engine lubricants, wherein a high degree of oxidation resistance and anti-corrosive properties is required, has been impractical because they have been too acidic and consequently too corrosive in lubricant mixtures. Attempts to reduce the acidity of halo-substituted aryl phosphates by caustic washing and/ or distillation have not produced a stable product. Haloaryl phosphates having a neutralization number immediately after distillation of the order of 0.5 to 1.0 are obtainable but they quickly deteriorateso that the haloaryl phosphate soon has a neutralization number about "o'rabove. The process of this invention provides a simple, efiective method of producing a halo-substituted aryl phosphate having a stable neutralization number below 1.0. Hereafter in description of the invention neutralization number and extreme pressure will often be abbreviated to Neut. No. and EP, respectively.

In accordance with this invention, halo-substituted aryl phosphates having a stable Neut. No. below 1.0, usually below 0.6, are produced by contacting a halosubstituted aryl phosphate with more than 2 weight 2,897,225 Patented July 28, 1959 anti-wear agent which does not degrade the anti-oxidant and anti-corrosive properties of a jet engine lubricant; The subject invention discloses how a di(o-chlorophenyl) phenyl phosphatehaving a stable Neut. No. below 1.0 and other: halo-substituted aryl phosphates of low. stable Neut. No. are produced.

Examples, of. haloaryl phosphates usedin the process ofthe'inventi'on are tri(p-chlorophenyl) phosphate, tri (pbromophenyl) phosphate, o,p-dichlorophenyl diphenyl phosphate, 'di(o-iodophenyl) phenyl phosphate, di(o-bromophenyl) phenyl phosphate, o-chlorophenyl diphenyl phosphate, li-chloro-ct-naphthyl diphenyl' phosphate, and mono-(p-iodophenyl) diphenyl phosphate. The invention is particularly useful in the preparation ofa low Neut. No. di(o-chlorophenyl) phenyl phosphate for use in synthetic base jet engine lubricants.

'An unusual feature of this invention is that other anhydrous alkalimetal carbonates such as anhydrous potassium carbonate, are ineffective in producing a halosubstituted aryl phosphate having a stable Neut. No. below 1.0. Anhydrous sodium bicarbonate is also ineffective in giving a halo-aryl phosphate having a Neut. No; below 1.0.

Bis-particularly surprising that treatment of a haloaryl phosphate" with anhydrous sodium carbonate under anhydrousconditionsresults in the production of a 107W Neut'No. product. Prior to this invention, it was believed necessary to use an aqueous alkaline solution to remove the acidic components present in haloarylphosphates. As indicated previously, it has notbeen possible to produce a product having a stable Neut. No. less than 2 by treatment with an aqueous alkaline solution. The surprising feature of this inventionis that the. acidic portions of thehaloaryl phosphate are eliminated nonionically under anhydrous conditions.

It. has been theorized that the success of the present invention resides in the avoidance of water during the removal of the acidic bodies from the haloaryl phosphates-- Apparently, the increase in Neut. No. normally associated with haloaryl phosphates, is attributable, at least in part, to their hydrolytic instability. Treatment of the haloaryl phosphates with sodium carbonate under percent anhydrous sodium carbonate under anhydrous conditions at a temperature less than about 160 F. The

halo-substituted aryl phosphate obtained by contact with anhydrous sodium carbonate at a temperature less than 160 F. retains a Neut. No. less than 1 during storage as long as anhydrous conditions are maintained.

t A modification of this invention which has been found effective is to store the halo-substituted aryl phosphate over anhydrous sodium carbonate. When desired for use'in, compounding of a lubricant, the halo-substituted aryl phosphate is simply separated by filtration from the anhydrous sodium carbonate over which it has been stored.

In a copending application Serial No. 512,304, filed May 31, 1955, it is disclosed that a jet engine lubricant of superior EP and anti-wear properties is formulated by'incorporation of a particular halo-substituted aryl phosphate, namely di(ochlorophenyl) phenyl phosphate, in an ester base lubricant. In the copendingapplication di(o-chlorophenyl) phenyl phosphate, having a Neut. No. less. than 5.0 is shown to be an outstanding EP and indicative of decomposition.

' anhydrous conditions eliminates the harmful effects of watercontamination.

An0therr surprising feature of the present invention is that a low ash product as Well as a low Neut. No. productisobtained by contact of the haloaryl phosphate with anhydrous sodium carbonate under anhydrous conditions at a temperature less than 150 F. Whatever .the mechanism by which the anhydrous sodium carbonate stably reduces the Neut. No. of the haloaryl phosphate, the ash concentration ofthe reaction products is of the same order of magnitude. Apparently,'the reaction products, whatever they may be, are insolublein the haloarylphosphate and are separated therefrom by filtration.

It is necessary to effectcontact between the haloaryl phosphate and anhydrous sodium carbonate at a temperature less than 160 F. in order to produce a waterwhite; product. At temperatures above 160" F., the resulting haloarylv phosphate has a decidedly purple color Temperatures lower than 60 F. can be used, but. itis recommended that a temperature above 60 F. be used since longer contact periods, are required at lower temperatures. As a general rule,gcontact is usually eifected at a temperature between and F.

order to obtain a low Neut. No. haloaryl phosphate. The 15 minute limitation is the time required at temperatures in the upper portion of the allowed range, that is between 130 and 160 F. There is no upper limitation on the time of contact of the haloaryl phosphate with the anhydrous sodium carbonate as is apparent from the fact that storage over anhydrous sodium carbonates at atmospheric conditions is a preferred modificatiomof theinvention.

The amount of anhydrous sodium carbonate required for conversion of the haloaryl phosphate to a product having the stable low Neut. No. is a minimum of about 2 weight percent of the phosphate treated. It is evident that there is no upper limit on the quantity of anhydrous sodium carbonate required with the exception of that imposed by expediency. Since excellent results are 1 obtained with 5 to weight percent sodium carbonate, there is no reason to use higher concentrations. As expected, longer contact times are required for lower concentrations of anhydrous sodium carbonate. At temperatures of 120150 F. and a concentration of 5 percent carbonate, 30 to 60 minutes of contact are recommended.

Contact of the anhydrous sodium carbonate with the haloaryl phosphate can be effected by a variety'of different contacting techniques. A static technique wherein the haloaryl phosphate is merely stored over anhydrous 7 7 sodium carbonate is effective but, as would be expected, requires a longer time of contact than a slurry technique wherein the liquid and solid anhydrous sodium carbonate are maintained in a state of agitation. Complicated contacting devices, such as counter-current flow of the liq- 7 7 uid phosphate and powdered anhydrous sodium carbonate, need not be used since excellent results are obtained by mere contact of the liquid and the solid anhydrous sodium carbonate.

The process of the invention is illustrated in the following examples.

EXAMPLE 1 Di(o-chlorophenyl) phenyl phosphate, having a Neut. No. of 4.6 and an ash of 0.17, was contacted with 5 weight percent anhydrous sodium carbonate at a temperature between 120 and 130 F. This testwas set up in quadruplicate and contact maintained in each of the four flasks for different periods of time ranging from 15 to 120 minutes. The results of this series of tests is shown in Table I in which the Neut. No. and ash of the product obtained at the difl erent times of contact are shown. a

The data in the above table indicate that optimum results, from the standpoint of Neut. No. and ash of the di-(o-chlorophenyl) phenyl phosphate, are obtained by 120 minutes of contact with 5% anhydrous sodium carbonate at a temperature of 120 to 130 F. The Neut. Nos. of the product obtained at 15, 30 and minutes are substantially identical, but .it is significant that the ash is improved by longer periods of contact.

EXAMPLE 2 Di-(o-chlorophenyl) phenyl phosphate, having the same Neut. No. and ash as the charge material in Example 1, was contacted at a temperature of 150 to 160F. with 5 weight percent anhydrous sodium carbonate in separate flasks for periods of 15 and 30 minutes. The properties of the resulting product at different time intervals are shown in Table II.

The data in the foregoing Table II prove thatonly 15 minutes of contact are required at temperatures between and F.

, EXAMPLE 3 Di-(o-chlorophenyl) phenyl phosphate, having the same Neut. No. and ash as the charge material in Example 1, was contacted with 10 weight percent anhydrous sodium carbonate for 15 minutes at a temperature of to 200 F. The resulting product had a Neut. No. of 0.32 and an ash of 0.19 but had a definite purple color indicating decomposition. The results obtained in this experiment indicate that temperatures of 190 to 200 F. are

- too high and that the temperature should be maintained at 160 F. or below duringcontact of the haloaryl phate with anhydrous sodium carbonate.

EXAMPLE 4 Di-(o-chlorophenyl) phenyl phosphate,' having" the same Neut. No. and ash as the charge material inYExample 1, was contacted with 0.5 weight percent anhydrous sodium carbonate at a temperature of 150 to 160 F. for 30 minutes. The resulting product had a Neut. No. of 2.5 and an ash of 0.48. The results obtained in this experiment indicate that the sodium carbonate concentration was too low to reduce efiectively 'theNeut. No. of a haloaryl phosphate to the desired level.

The foregoing examples prove the efiectiveness of the process of this invention inprodu'cinga stable haIoaryl phosphate having a Neut. No. well below 1.0. The following examples demonstrate that this action is. highly specific to anhydrous sodium carbonate.

EXAMPLE .5

Di(o-chlorophenyl) phenyl phosphate having a Neut. No. of 4.9 and an ash of 0.17 was contacted with 5 weight percent anhydrous potassium carbonate at a temperature of about 150 F. for 30 minutes. The resulting product had a Neut. No. of 3.5 and an ash of 0.97. The results obtained in this experiment indicate that anhydrous potassium carbonate is substantially inefl'fective at conditions of temperature and concentration at which anhydrous sodium carbonate gave outstanding results as indicated Example 2. K

phos- EXAMPLE 6 7 Di(o-chlorophenyl) phenyl phosphate, having the same Neut. No. and ash as the charged material in Example 5 was contacted with 5 weight percent anhydrous sodium bicarbonate at'a temperature of about 150 F. for 40 minutes The resulting product had a Neut. No. of 2.5. The results of this experiment show that 'anhydrous bicarbonate .is inefiective in pro ducin g a low Neut.}lo.haloarylphosphate, 7 7

All the foregoing examples have been run; with' d i( ochlorophenyl) phenylphosphate but similar results are obtained with other haloaryl phosphates such as, tri(pchlorophenyl) phosphate, tri(p-bromophe nyl) phosphate, o,p-dichloropheny1andvdiphenylphosphateh 7 7 7 Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process for producing a stable haloaryl phosphate of low acidity which comprises contacting said haloaryl phosphate under anhydrous conditions with at least 2 weight percent of anhydrous sodium carbonate at a temperature between 60 and 160 F. for a minimum of at least 15 minutes.

2. A process according to claim 1 in which the anhydrous sodium carbonate concentration is between 5 and weight percent of the haloaryl phosphate.

3. A process according to claim 1 in which contact of the haloaryl phosphate with the anhydrous sodium car- 2,542,604

6 bonate is effected at a temperature between and F.

4. A process for producing di(o-ch1oropheny1) phenyl phosphate having a stable Neut. No. below 1.0 which comprises contacting said phosphate under anhydrous conditions with at least 2 weight percent anhydrous sodium carbonate at a temperature between 60 and F. for a period of at least 15 minutes.

References Cited in the file of this patent UNITED STATES PATENTS 2,170,833 Moyle Aug. 15, 1939 2,220,113 Moyle Nov. 5, 1940 Weisel et a1 Feb. 20, 1951 

1. A PROCESS FOR PRODUCING A STABLE HALOARYL PHOSPHATE OF POW ACIDITY WHICH COMPRISES CONTACTING SAID HALOARYL PHOSPHATE UNDER ANHYDROUS CONDITIONS WITH AT LEAST 2 WEIGHT PERCENT OF ANHYFROUS SODIUM CARBONATE AT A TEMPERATURE BETWEEN 60 AND 160* F, FOR A MINIMUM OF AT LEAST 15 MINUTES. 